LAX and LAS are the two locations I've had the best luck getting consistent PCAR availability, with SEA being a somewhat close third. I haven't been able to find the rhyme or reason in any meaningful way that is visible to the consumer, so I just chalk it up to fleet planning... my comments above about Nav on PCARs makes me care less about booking an LCAR since the beginning of '15 anyway. Even with a PCAR res I still end up going to ES often enough when they don't have an ER-PREM operating and/or point me to an Impala 2LT or Maxima on ES anyway.